1p9i
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(New page: 200px<br /><applet load="1p9i" size="450" color="white" frame="true" align="right" spinBox="true" caption="1p9i, resolution 1.17Å" /> '''Coiled-coil X-ray st...)
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Revision as of 00:06, 25 November 2007
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Coiled-coil X-ray structure at 1.17 A resolution
Overview
We determined the 1.17 A resolution X-ray crystal structure of a hybrid, peptide based on sequences from coiled-coil regions of the proteins GCN4, and cortexillin I. The peptide forms a parallel homodimeric coiled-coil, with C(alpha) backbone geometry similar to GCN4 (rmsd value 0.71 A). Three, stabilizing interactions have been identified: a unique hydrogen, bonding-electrostatic network not previously observed in coiled-coils, and, two other hydrophobic interactions involving leucine residues at positions, e and g from both g-a' and d-e' interchain interactions with the, hydrophobic core. This is also the first report of the quantitative, significance of these interactions. The GCN4/cortexillin hybrid, surprisingly has two interchain Glu-Lys' ion pairs that form a hydrogen, bonding network with the Asn residues in the core. This network, which was, not observed for the reversed Lys-Glu' pair in GCN4, increases the, combined stability contribution of each Glu-Lys' salt bridge across the, central Asn15-Asn15' core to approximately 0.7 kcal/mole, compared to, approximately 0.4 kcal mole(-1) from a Glu-Lys' salt bridge on its own. In, addition to electrostatic and hydrogen bonding stabilization of the, coiled-coil, individual leucine residues at positions e and g in the, hybrid peptide also contribute to stability by 0.7 kcal/mole relative to, alanine. These interactions are of critical importance to understanding, the stability requirements for coiled-coil folding and in modulating the, stability of de novo designed macromolecules containing this motif.
About this Structure
1P9I is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Unique stabilizing interactions identified in the two-stranded alpha-helical coiled-coil: crystal structure of a cortexillin I/GCN4 hybrid coiled-coil peptide., Lee DL, Ivaninskii S, Burkhard P, Hodges RS, Protein Sci. 2003 Jul;12(7):1395-405. PMID:12824486
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